Some firearms, such as modular or reconfigurable firearms, may be adapted to fire multiple caliber, different length, and/or different sized or configured rounds. For example, some military or tactical firearms are designed to be reconfigurable to fire .308, .338 or .300 Winchester Magazine (“Win. Mag.”) rounds, which rounds may include belted and non-belted rounds, and consequently may require a differently configured magazine to store and feed the rounds into the chamber of the firearm. It therefore can be seen that a need exists for a reconfigurable magazine that accommodates such variably configured, sized, and/or caliber rounds to ensure proper storage of the rounds and reliable feeding thereof. The present disclosure addresses the foregoing and other related, as well as unrelated, issues in the art.